403 errors on trying to update plugin settings

I am having this problem on both Pro Sites and Advertising. Trying to update the plugin settings results in a 403 error from the server. Specifically, I am trying to update both the number of pages that ads appear on (changing it from 1 to 3) and the Google ad code. The server owner says there is nothing in the configuration that should be causing this to happen. This is a Litespeed server. I have checked plugin permissions, but they are all set to 755. I haven't had this issue before, and was wondering if it might be cause by a recent update.